Preparation Of Ion Exchangers Research Articles

Sequential diethylaminoethyl dextran-grafting and diethylaminoethyl modification improve the adsorption performance of anion exchangers

Ion exchangers with high adsorption capacity, fast mass transfer, and high salt-tolerance synchronously are highly desired for high-performance protein purification. Here, we propose a sequential diethylaminoethyl dextran-grafting and diethylaminoethyl chloride modification strategy to achieve high-performance anion exchangers. The advantages of the double-modification strategy lie in: (1) the introduction of diethylaminoethyl in the second modification has no diffusion limitation due to the small molecular size, thus a high ionic capacity; (2) the grafting ligands not only provide three-dimensional adsorption space for high adsorption capacitybut alsofacilitate surface diffusion of protein by chain delivery. The maximum adsorption capacity of the obtained anion exchangers for bovine serum albumin reaches 333 mg/mL, the ratio of effective pore diffusivity (De) to free solution diffusivity (D0) reaches 0.69, and the adsorption amount reaches 97 mg/mL even in 100 mmol/L NaCl concentration,. All these results demonstrate the proposed sequential modification strategy are promising for the preparation of high-performance ion exchangers.

Synthesis of new immobilized N-chloro-sulfonamides and release of active chlorine from them

A method has been developed for the synthesis of granular polymeric materials with immobilized N-chloro-sulfonamide groups. Commercially available resin polymers widely applied for the preparation of ion exchangers have been used as polymer carriers. The elaborated technological conditions make it possible to modify these resins with a high conversion degree, without deteriorating the strength characteristics, and with the possibility of regulating the concentration of active chlorine over a wide range (up to 11 % w/w). The structure of the synthesized polymers was confirmed by IR spectroscopy data. To determine the concentration of functional groups, a special method of iodometric titration has been developed. The processes of emission of active chlorine from synthesized polymers into aqueous solutions have been studied. It has been shown that this process significantly depends on the composition of the solution: no release of active chlorine into distilled water is observed, and when using tap water, its concentration is reached 5–8 mg/dm3 and remains up to 30 days when the granules are in water. The processes of activation of active chlorine emission by compounds of amine nature have been studied, the corresponding kinetic curves of the dependence between change in the concentration of active chlorine in solution and the used activator are presented. It has been found that the nature of the used activator strongly affects, among other things, the stability of the obtained chlorine-active solutions. Taurine and sulfamic acid are found to be the optimal activators for obtaining stable solutions of active chlorine of high concentration. The composition of the N-chloro-taurin solution obtained in this way has been additionally analyzed by UV spectroscopy. Thus, the synthesized polymers make it possible to quickly in situ obtain high-purity solutions of active chlorine without the use of special electrochemical equipment. The polymers themselves are compact, stable, and can be repeatedly regenerated

MODIFYING WASTE POLYSTYRENE TO ION EXCHANGE MATERIAL: OPTIMIZING THE SULFONATION PROCESS AND COLUMN STUDY FOR THE REMOVAL OF Cr3+

The incredible growth of plastic waste is a major concern for the whole society in recent years. The accumulation of plastic waste has badly effects on wildlife, habitat, and humans. Plastics that act as pollutants are categorized into different sizes, from micro to macro. Disposable plastic waste was collected at the bakery shop and removed the residue food by tap water and NaOH 1M to remove residual food. This study focuses on modify waste plastic by sulfuric acid to bind the sulfonated function group on the structure of the polystyrene chain at room temperature. The sulfonated product was used for removing heavy metal ion in water with the mechanism of the ion exchange process. The prepared ion exchange material was characterized by FTIR and SEM to ensure that the sulfonation process has happened. The chromium (III) ion removal by modified ion exchange product in continuous mode was affected by an operational parameter such as the bed height of sulfonated material. The Yoon-Nelson and Thomas model were used to analyze the experimental result and the model parameters were evaluated. From this result, it can be concluded that with the increasing amount of sulfonated waste polystyrene, exchange capacity, and the time required for a 50% adsorbate breakthrough was higher.

Highly efficient dye removal and lysozyme purification using strong and weak cation-exchange nanofiber membranes

Electrospinning technology was applied for the preparation of polyacrylonitrile (PAN) nanofiber membrane in this work. After hot pressing, alkaline hydrolysis and neutralization treatment, a weak acid cation exchange membrane (P-COOH) was prepared. By the covalent coupling reaction between the acidic membrane and aminomethane sulfonic acid (AMSA), a strong acidic nanofiber membrane (P-SO3H) was obtained. The surface morphology, chemical structure, and thermal stability of the prepared ion exchange membranes were analyzed via SEM, FTIR and TGA. Analytical results showed that the membranes were prepared successfully and thermally stable. The ion exchange membrane (IEX) was conducted with the newly designed membrane reactor, and different operating conditions affecting the adsorption efficiency of Toluidine Blue dye (TBO) were investigated by dynamic flow process. The results showed that dynamic binding capacity (DBC) of weak and strong IEX membranes for TBO dye was ~170 mg/g in a dynamic flow process. Simultaneously, the ion exchange membranes were also used for purifying lysozyme from chicken egg white (CEW). Results illustrated that the recovery yield and purification factor of lysozyme were 93.43% and 29.23 times (P-COOH); 90.72% and 36.22 times (P-SO3H), respectively. It was revealed that two type ion exchange membranes were very suitable as an adsorber for use in dye waste treatment and lysozyme purification process. P-SO3H strong ion-exchange membrane was more effective either removal of TBO dye or purification of lysozyme. The ion exchange membranes not only effectively purified lysozyme from CEW solution, but also effectively removed dye from wastewater.

Solvothermal ion exchange preparation of Bi11VO19 to sensitize TiO2 NTs with high photoelectrochemical performances

Ag3VO4 nanograss was deposited on the surface of vertically grown TiO2 nanotube arrays (TiO2 NTs) by a successive ion layer adsorption and reaction (SILAR) method, and the Ag3VO4 nanograss was further transformed into Bi11VO19 by the solvothermal ion exchange method. The formation of Bi11VO19 was influenced by solvothermal intervals, and the TiO2 NTs/Bi11VO19 exhibited outstanding visible light response and photoelectrochemical activity. The TiO2 NTs/Bi11VO19 (3) prepared with solvothermal treatment for 3 h showed the optimal photoelectric conversion and photoelectrocatalytic (PEC) properties. The transient photocurrent density, photovoltage and charge carrier concentration achieved 9.53 mA/cm2, −0.29 V and 1.36 × 1020 cm−3, respectively. Furthermore, the PEC rate constants of TiO2 NTs/Bi11VO19 (3) for the MO, RhB and MB degradation achieved 3.56 × 10−3, 9.01 × 10−3 and 2.30 × 10−2 min−1, respectively. The PEC removal efficiency of Cr(VI) was 86.62%. The outstanding photoelectric activity drives the TiO2 NTs/Bi11VO19 photoelectrode prospective applications in waste-water purification and solar cells.

Preparation of ion-exchange supports via activation of epoxy-SiO2 with glycine to immobilize microbial lipase – Use of biocatalysts in hydrolysis and esterification reactions

Ion-exchange supports have been prepared via sequential functionalization of silica-based materials with (3‑Glycidyloxypropyl)trimethoxysilane (GPTMS) (Epx-SiO2) and activation with glycine (Gly-Epx-SiO2) in order to immobilize lipase from Thermomyces lanuginosus (TLL) via adsorption. Rice husk silica (RHS) was selected as support with the aim of comparing its performance with commercial silica (Immobead S60S). Sequential functionalization/activation of SiO2-based supports has been confirmed by AFM, SEM and N2 adsorption-desorption analyses. Maximum TLL adsorption capacities of 14.8 ± 0.1 mg/g and 16.1 ± 0.6 mg/g using RHS and Immobead S60S as supports, respectively, have been reached. The Sips isotherm model has been used which was well fitted to experimental data on TLL adsorption. Catalytic activities of immobilized TLL were assayed by olive oil emulsion hydrolysis and butyl stearate synthesis via an esterification reaction. Hydrolytic activity of the biocatalyst prepared with a commercial support (357.6 ± 11.2 U/g) was slightly higher than that of Gly-Epx-SiO2 prepared with RHS (307.4 ± 7.2 U/g). On the other hand, both biocatalysts presented similar activity (around 90% conversion within 9–10 h of reaction) and reusability after 6 consecutive cycles of butyl stearate synthesis in batch systems.

Synthesis and Characterization of Nanocomposite Ion Exchanger for the Removal of Heavy Metals

In material science, organic-inorganic hybrid materials have attracted a great deal of attention prepared by sol-gel approach. Organic polymer part of the composite provides chemical stability and mechanical strength whereas the inorganic part supports the ion-exchange behavior and thermal stability. Such modified composite materials can be applied as an electrochemically switchable ion exchanger for water treatment, especially water softening. Polyaniline zirconium (IV)iodate nanocomposite ion exchanger is prepared by sol-gel method. Polyaniline zirconium (IV)iodate nanocomposite ion exchanger is synthesized and characterized by Fourier transform-infrared spectra (FTIR), ultraviolet-visible spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo gravimetric analysis (TGA), ion exchange, conductivity, and antimicrobial studies. The synthesis process of the polyaniline zirconium (IV)iodate nanocomposite ion exchanger was discussed. The route reported here may be used for the preparation of other nanocomposite ion exchangers.

Molten Ag2 SO4 -based Ion-Exchange Preparation of Ag0.5 La0.5 TiO3 for Photocatalytic O2 Evolution.

Ag0.5 La0.5 TiO3 with an ABO3 perovskite structure was synthesized by a newly developed ion-exchange method. Molten Ag2 SO4 instead of traditional molten AgNO3 was used as Ag+ source in view of its high decomposition temperature (1052 °C), thereby guaranteeing the complete substitution of Ag+ for Na+ in Na0.5 La0.5 TiO3 with a stable ABO3 perovskite structure at a high ion-exchange temperature (700 °C). Under full-arc irradiation, the O2 -evolution activity of Ag0.5 La0.5 TiO3 was about 1.6 times that of Na0.5 La0.5 TiO3 due to the optimized electronic band structures and local lattice structures. On the one hand, the substitution of Ag+ for Na+ elevated the VBM and thus narrowed the band gap from 3.19 to 2.83 eV, thereby extending the light-response range and, accordingly, enhancing the photoexcitation to generate more charge carriers. On the other hand, the substitution of Ag+ for Na+ induced a lattice distortion of the ABO3 perovskite structure, thereby promoting the separation and migration of charge carriers. Moreover, under visible-light irradiation, Ag0.5 La0.5 TiO3 displayed notable O2 evolution whereas Na0.5 La0.5 TiO3 showed little O2 evolution, thus demonstrating that the substitution of Ag+ for Na+ enabled the use of visible light to evolve O2 photocatalytically. This work presents an effective route to explore novel Ag-based photocatalysts.

無機イオン交換体の合成および結晶化学に関する研究

無機イオン交換体の合成および結晶化学に関する研究

Ion-Exchange Behavior of New and Novel Zirconium(IV)-Based Composite Cation-Exchangers

ABSTRACTThe synthesized polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate composite ion exchangers were characterized by Fourier transform infrared spectroscopy, UV spectra, X-ray diffraction, scanning electron microscope, thermogravimetric analysis, and conductivity studies. The ion-exchange capacities, effect of eluent concentration, elution time, elution behavior, and pH on ion-exchange capacity were also studied to exploit the ion-exchange capability of the composites. The study revealed that polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate ion exchangers are having excellent ion-exchange capacity values for K+ ion 1.36 and 1.44 meq g−1, respectively. The organic polymeric part of the composites provides mechanical and chemical stability, whereas the inorganic part supports the ion-exchange behavior and thermal stability. The increase in electrical conductivity is due to the inorganic and organic parts. A mechanism for the formation of the polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate composite ion exchangers is discussed, which may also be applied for the preparation of other composite ion exchangers. Sorption behavior of metal ions on the composites was studied in different solvent systems. On the basis of distribution coefficient values (Kd), it has been found that the cation-exchange materials are highly selective for Pb(II)-ions. Such modified composite materials can be applied as an electrochemically switchable ion exchanger for water treatment, especially water softening.

(Invited) Development of Reverse Electrodialysis System

Salinity gradient power (SGP), also called blue energy, is a newly emerging form of marine renewable energy. SGP is the energy available from the salinity difference between seawater and river water, which respectively have high and low salt concentrations. The SGP energy potential between typical seawater and river water is 231 m (~23 atm) of hydraulic water head. The global energy potential is estimated to be 2.4–2.6 TW, which is ~80% of the global electricity demand. Among membrane-based blue energy technologies, reverse electrodialysis (RED), the opposite process of electrodialysis (ED), has been applied practically. Recently, RED has been considered the attractive technology because this new process has huge potential and possibility to generate energy from abundant but largely unused resources. RED uses a stack of alternating cation (CEM) and anion (AEM) exchange membranes. For RED to find greater use, a high power density (power generated per membrane area) is essential. By increasing the power density, the membrane demand and RED stack size can be decreased. To make RED an economically attractive technology, the large scale RED stack should be developed. Recently, we have developed the kW class RED stack and evaluated the performances for the first time in Korea. And the effect of operation conditions on power density was confirmed. Furthermore, a numerical simulation has been conducted for investigating the flow distribution and pressure loss in the stack. Since the performance of RED significantly depends on the inertial fluid characteristics and the required pumping power, it is a primary importance to lower pressure drop and uniform flow distribution in the stack. With respect to the size and the height of cell, and the inlet shape of cell, the flow distribution and the pressure loss have been evaluated. The ion exchange membranes (IEMs) also strongly influences the performance, specifically, the power density, of the RED stack. Although studies have, over the last decade, improved the IEM characteristics, they do not yet match the expected characteristics for RED. Generally, IEMs for ion separation processes require high strength and long lifetime regardless of the electrical resistance and thickness; however, IEMs for RED require low electrical resistance and high permselectivity. Nevertheless, most present IEMs for RED still do not possess both the thinness and the mechanical strength required for higher power density of the RED stack. To solve this problem, we have developed pore-filling-type IEMs for RED. A pore-filling membrane consists of a very thin porous substrate to provide mechanical strength and an electrolyte polymer in the substrate pores to allow ion conductivity. Meanwhile, electrolyte-polymer-filled pores should have high ion exchange capacity (IEC) to increase the ion conductivity. The thickness of the prepared pore filling membranes was controlled between 20 and 25 micrometers to extremely lower membrane resistance and to increase ion transfer. The prepared ion exchange pore filling membranes were compared with commercial membranes. We obtained the highest power density comparing to the result reported in elsewhere.

Acid and base recovery from brine solution using PVP intermediate-based bipolar membrane through water splitting technology

Potable water has become a scarce resource in many countries. In fact, the world is not running out of water, but rather, the relatively fixed quantity is becoming too contaminated for many applications. Hence, the present work was designed to evaluate the desalination efficiency of resin and glass fiber-reinforced Polysulfone polymer-based monopolar and bipolar (BPM) ion exchange membranes (with polyvinyl pyrrolidone as the intermediate layer) on a real sample brine solution for 8 h duration. The prepared ion exchange membranes (IEMs) were characterized using FTIR, SEM, TGA, water absorption, and contact angle measurements. The BPM efficiency, electrical conductivity, salinity, sodium, and chloride ion concentration were evaluated for both prepared and commercial-based IEM systems. The current efficiency and energy consumption values obtained during BPMED process were found to be 45 % and 0.41 Wh for RPSu-PVP-based IEM system and 38 % and 1.60 Wh for PSDVB-based IEM system, respectively.

Ion-exchange sample preparation for the determination of anions in highly alkaline solutions by ion chromatography

A sample preparation procedure is proposed for the analysis of highly alkaline solutions; it includes the addition of a dosed amount of a specially prepared ion exchanger to a container with the analyzed solution, phase equilibration, and the decantation of a liquid phase. The procedure was applied to the determination of the anionic composition of the sample of an alkaline condensate of fumarole gases by ion chromatography.

Highly Durable and Efficient Pore Filling Type Ion Exchange Membranes for Reverse Electrodialysis

Highly durable ion exchange pore filling membranes (cation exchange membranes and anion exchange membranes) with high ion transfer coefficients have been developed for reverse electrodialysis as an energy conversion system. The polymer electrolytes in both cases of cation exchangeable and anion exchangeable ones consisting of the whole hydrocarbon materials were introduced into porous hydrocarbon substrates and crosslinked by radical polymerization in this work. The thickness of the prepared pore filling membranes was controlled between 20 and 25 micrometers to extremely lower membrane resistance and to increase ion transfer. The prepared ion exchange pore filling membranes were characterized by using dimensional stability, membrane area resistance, ion transport number, and phisico-chemical stability. Also the thermal and the structural properties of the prepared membranes were determined. Meanwhile, all the properties of the prepared membranes were compared with commercial membranes obtained from Tokuyama, Fuji, and Fuma-Tech. Furthermore, RED cell performance and energy efficiency using the prepared pore filling membranes were also evaluated. Finallly we obtained a world best cell power density when comparing to the result reported in elsewhere.

In situ ion exchange preparation of AgBr/Ag3PO4/HAP nanocomposite photocatalyst with enhanced visible light photocatalytic performance

A novel AgBr/Ag3PO4/HAP (Ca10(PO4)6(OH)2) nanocomposite photocatalyst was prepared by a facile in situ ion exchange route. X-Ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and UV–vis diffuse reflectance spectroscopy techniques were used to investigate the phase structure, composition, morphology and optical property of the AgBr/Ag3PO4/HAP product. Under visible light irradiation, as-synthesized AgBr/Ag3PO4/HAP catalyst exhibited the higher visible light photocatalytic activity than Ag3PO4/HAP and AgBr/Ag3PO4, and displayed a better stability compared with Ag3PO4/HAP. The AgBr/Ag3PO4/HAP photocatalyst had a higher photodegradation rate for rhodamine B (RhB, a cationic dye) than methyl orange (MO, an anionic dye) and showed the excellent photoactivity in the acid solution or in the basic solution. The superoxide radicals (O2−•) and holes (h+) were considered to be the main active species for dye degradation in the AgBr/Ag3PO4/HAP suspension.

Relationships between transport and physical–mechanical properties of ion exchange membranes

This review focuses on the characterization of properties of ion exchange membranes, on the compromises between ion exchange capacity, relative water content and electrochemical properties of ion exchange membranes. Properties of heterogeneous ion exchange membranes prepared from polyethylene as matrix, ion exchange resin powder and polyester fabric were studied. Ion exchange membranes were prepared with using different ion exchange resins. These ion exchange membranes can be used in many electro separation processes like electro dialysis, electrode ionization, membrane electrolysis or electrophoresis. Desalination of brackish and surface water, purification of waste water or mine water, water desalination after tertiary biological treatment, purification of organic substances, stabilization of wine or demineralization of whey are the most frequent applications where these prepared ion exchange membranes can be utilized. All prepared ion exchange membranes were characterized with same methods and monitored the parameters of ion exchange membranes were ion exchange capacity using Mohr method, electric resistance measured in a special experimental cell using a compensation method, permselectivity measured in the same measuring cell as electric resistance and relative water content. The relationships between the transport and physical–mechanical properties were found. An ion exchange membrane with specific required properties can be prepared on the basis of resultant values of monitored properties.

Application of Ambient-Temperature Argon Plasma Modified PET Fibers with Surface Grafting for Heavy Metal Removal

The present study utilized the capability of ambient-temperature plasma in modifying the surface properties of materials to activate the polyethylene terephthalate (PET) fiber surfaces. The effects of different plasma treatment parameters (such as plasma power, treatment time) and grafting parameters (such as grafting temperature, acrylic acid monomer concentration, grafting time) on the activation and grafting of the PET fibers were studied. The feasibility of applying ambient-temperature plasma combined with grafting technology for the preparation of ion exchangers in the heavy metal containing wastewater treatment was evaluated.

Ion-exchange preparation for visible-light-driven photocatalyst AgBr/Ag2CO3 and its photocatalytic activity

The AgBr/Ag2CO3 composite was synthesized by an ion-exchange reaction. The physical and chemical properties of the catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), diffuse-reflection spectra (DRS) and photocurrent techniques. The photocatalytic performance of the samples was evaluated by photocatalytic oxidation of methylene blue (MB) dye under visible-light irradiation. The XRD, SEM-EDS, TEM, and XPS analyses indicated that the heterojunction structure had been obtained. The results indicated that the AgBr/Ag2CO3 heterojunction had exhibited a much higher photocatalytic activity than the pure Ag2CO3. The enhancement of photocatalytic activity was related to the efficient separation of electron–hole pairs because of the stagger band potentials between AgBr and Ag2CO3.

Studies on Ion-Exchange Properties of Polyaniline Zr(IV) Tungstoiodophosphate Nanocomposite Ion Exchanger

Organic-inorganic hybrid materials prepared by sol-gel approach have attracted a great deal of attention in material science. Organic polymeric part of the composite provides mechanical and chemical stability whereas the inorganic part supports the ion-exchange behaviour and thermal stability and also increases the electrical conductivity. Such modified composite materials can be applied as an electrochemically switchable ion exchanger for water treatment, especially water softening. Polyaniline zirconium(IV) tungstoiodophosphate nanocomposite ion exchanger is prepared by sol-gel method. Polyaniline zirconium(IV) tungstoiodophosphate nanocomposite ion exchanger is synthesized and characterized by Fourier transform-infrared spectra, ultraviolet-visible spectra, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, ion exchange, conductivity, and antimicrobial studies. A mechanism for the formation of the polyaniline zirconium(IV) tungstoiodophosphate nanocomposite ion exchanger was discussed. The route reported here may be used for the preparation of other nanocomposite ion exchangers.

The Effects of Sulfonated Poly(ether ether ketone) Ion Exchange Preparation Conditions on Membrane Properties.

A low cost cation exchange membrane to be used in a specific bioelectrochemical system has been developed using poly(ether ether ketone) (PEEK). This material is presented as an alternative to current commercial ion exchange membranes that have been primarily designed for fuel cell applications. To increase the hydrophilicity and ion transport of the PEEK material, charged groups are introduced through sulfonation. The effect of sulfonation and casting conditions on membrane performance has been systematically determined by producing a series of membranes synthesized over an array of reaction and casting conditions. Optimal reaction and casting conditions for producing SPEEK ion exchange membranes with appropriate performance characteristics have been established by this uniquely systematic experimental series. Membrane materials were characterized by ion exchange capacity, water uptake, swelling, potential difference and NMR analysis. Testing this extensive membranes series established that the most appropriate sulfonation conditions were 60 °C for 6 h. For mechanical stability and ease of handling, SPEEK membranes cast from solvent casting concentrations of 15%–25% with a resulting thickness of 30–50 µm were also found to be most suitable from the series of tested casting conditions. Drying conditions did not have any apparent impact on the measured parameters in this study. The conductivity of SPEEK membranes was found to be in the range of 10−3 S cm−1, which is suitable for use as a low cost membrane in the intended bioelectrochemical systems.